The Hubble space telescope was a total bust after it was dropped from space shuttle Discovery 20 years ago. But some fine tuning turned it into a grand scientific achievement.

Here are some of greatest discoveries and spectacular images from the orbiting space observatory which is about the size of a school bus.

Credit: NASA

A new photo from the recently refurbished Hubble Space Telescope shows one of the largest star-birth sections in the Carina galaxy.

NASA describes the image: "The image captures the top of a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby bright stars. The pillar is also being pushed apart from within, as infant stars buried inside it fire off jets of gas that can be seen streaming from towering peaks like arrows sailing through the air."

Credit: NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI)

Hubble captured this pair of gravitationally interacting galaxies called Arp 147 forming at "10," as scientists tested the newly installed prime working camera, the Wide Field Planetary Camera 2 (WFPC2).

Credit: NASA, ESA, and M. Livio (STScI)

One of the top discoveries from Hubble include the age of the universe. From 1996 and 1997 images, the distance from Earth to galaxy NGC 4603 was determined to be 108 million light years. Extrapolating backward theorizes that the Big Bang happened between 9 and 14 billion years ago. In recent years the Hubble has helped make even more precise measurements.

Another huge Hubble discovery was a missing link in what we knew about planet formation. Here's how NASA descibes it" "Take light and fluffy stardust, condense to rocks. It's the "condense to rocks" part scientists have been eager to see. Like making a pizza, a cloud of stardust has to go from a blob to a relatively flat disk to form a new star and planet system." Here's a piece of Orion where planets are forming.

Credit: NASA

In 2007 the Hubble detected the first-ever organic molecule in the atmosphere of a planet orbiting outside our solar system. An artist's view of planet HD 189733b.

Credit: NASA/ESA/G. Bacon (STScI)

In 2001, Hubble observed an explosion 10 billion light-years from our planet greatly bolsters the case for the existence of a mysterious form of "dark energy" pervading the cosmos.

Credit: NASA and A. Reiss

Throughout its lifetime in orbit, some of the most spectacular images have been of mysteries from outside our solar system. The Cone Nebula is 7 light-years long and 2,500 light-years away from Earth, according to NASA.

Credit: NASA

This image, taken by the newly installed Wide Field Camera 3, shows the Butterfly Nebula (or Bug Nebula, cataloged as NGC 6302), at the center of which is a dying star that once had five times the mass of Earth's sun. Gas that was released by a dying star shoots through space at a speed in excess of 600,000 miles an hour.

Credit: NASA

This image is a composite of images taken from the Hubble Space Telescope, Chandra X-Ray Observatory and Spitzer Space Telescope. X-ray data recorded by Chandra appears in blue, infrared light recorded by Spitzer appears in red, and Hubble's observation of hydrogen emission appears in orange.

This composite image of the Helix Nebula was taken with both the Hubble's Advanced Camera for Surveys and the Mosaic II camera on the 4-meter telescope at Chile's Cerro Tololo Inter-American observatory.

Credit: NASA

Messier 82 - where stars are born.

Taken from X-rays, visible light and infrared observations, this ACS composite image shows Kepler's supernova remnant radiation. Each color represents a different point on the light spectrum, including those usually invisible to the naked eye.

Credit: NASA

In 2003, Hubble took a series of observations of the Sombrero Galaxy (aka M104), which is 50,000 light-years wide, over about a month's time. The galaxy lies on the edge of the Virgo galaxy cluster, 28 million light-years from the Earth. The Sombrero Galaxy is equivalent to 800 billion suns in mass.

Credit: NASA

The Wide Field Camera 3 captured this still life of Stephan's Quintet, a group of five galaxies. At the top right is NGC 7319, a barred spiral, and those blue and red specks are clusters of thousands of stars. At the center are two galaxies that appear from this perspective almost as one, where there's "a frenzy of star birth" going on. At bottom left is NGC 7317, which NASA describes as "a normal-looking elliptical galaxy."??At upper left is the dwarf galaxy NGC 7320, where the blue and pink dots represent bursts of star formation. It's actually much closer to Earth (40 million light-years away) than the other four galaxies here.

Credit: NASA

NASA scientists stitched together a mosaic of 78 exposures taken by the ACS, showcasing 80 galaxies.

Credit: NASA

The arcs and streaks in galaxy cluster Abell 370 reveal "gravitational lensing," the distortion of light from far-off, background galaxies by the cluster's gravitational field. The lensing effect helps astronomers measure the distribution of dark matter in galaxy clusters.

Credit: NASA

A blob of matter, called HST-1, was ejected from a black hole, giving us a spectacular light show. The Hubble had been tracking this activity for 7 years.

Credit: NASA, ESA, and J. Madrid (McMaster University)

From images taken by NASA's Hubble Space Telescope, for the first time astronomers have spotted a planet orbiting a star outside our solar system.

The planet, Fomalhaut b, maintains an orbit around the star Fomalhaut and has three times the mass of Jupiter.

Credit: NASA

Hubble has recorded events in our solar system. On July 24, 1994, the Hubble grabbed headlines with spectacular pictures of the Comet Shoemaker-Levy breaking up and then crashing into Jupiter. There are actually eight different crash sites in this photo.

Credit: NASA

On July 4-5, 2005, Hubble recorded the impact of a projectile that was launched by the spacecraft Deep Impact on a comet.

Hubble captured four of Saturn's largest moons passing in front of the planet at the same time. Titan is the orange moon casting the northern most shadow. Near the ring plane is Mimas. Farther to the left are the bright moon Dione and the fainter moon Enceladus.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

A solar eclipse is rare on Earth, but this photo shows three occurring at the same time on Jupiter. In this Hubble image, three of Jupiter's 16 confirmed moons cast shadows that create black spots. From left to right, they are cast by Ganymede, Io and Callisto. Two of the moons are also visible in this image. Io is the white spot toward the center of the planet; Ganymede is the blue spot in the upper right. Callisto is outside the frame.

Credit: NASA

Images from the Hubble Space Telescope confirm the appearance of a third giant red spot on Jupiter (the smaller spot to the left). The new feature was recently seen as a white storm raging near the other two red spots, but astronomers believe that it grew so large that it dredged up material beneath the planet's cloud cover, causing it to turn red.

The Great Red Spot is a storm that's wider than two Earths and has been spotted on Jupiter for at least 168 years and most likely longer. Red Spot Jr. turned red in early 2006.

Credit: NASA

Neptune - the last planet in the solar system.

Credit: NASA

It's just a few pixels wide but it's one of the few we have of the former planet, now dwarf planet, Pluto.

NASA says there are 100,000, all squeezed (relatively speaking) into a small portion of the Omega Centauri star cluster. The yellow-white dots are adult stars powered by hydrogen fusion, the orange ones are late-life stars, and the red giants, which are shedding their gaseous envelopes, are older still.

Credit: NASA

Carinae is a doomed star that was one of the brightest in the sky in 1843, disappeared from sight, and returned in 1998 and 1999 when its brightness doubled.

Credit: NASA

The maintenance contract on the Hubble has run out. If there are any problems, scientists on Earth will have to deal with them. But the James Webb Space Telescope is set to launch in 2013 and will study the origins of the universe.

Credit: NASA

The deepest image of the universe ever taken in near-infrared light. The faintest and reddest objects in the image are galaxies that formed 600 million years after the Big Bang.

A new photo from the recently refurbished Hubble Space Telescope shows one of the largest star-birth sections in the Carina galaxy.

NASA describes the image: "The image captures the top of a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby bright stars. The pillar is also being pushed apart from within, as infant stars buried inside it fire off jets of gas that can be seen streaming from towering peaks like arrows sailing through the air."

Credit: NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI)